After reading the config for recipes, I saw coffee and gave it a try. The config says:

  name: Stale Coffee/Coffee/Strong Coffee
  ingredients:
  - INK_SACK,3/12
  - MILK_BUCKET/2
  cookingtime: 2
  color: BLACK
  difficulty: 3
  effects:
  - REGENERATION/1/2-5
  - SPEED/1/30-140

I read it as cook 3-12 ink sacks and two milk buckets in a cauldron for 2 minutes. However, after trying 12, 6, and 3 ink sacks, it still only gives me a "Colored brew". Any ideas on what's happening?